1. Field of the Invention
The present invention relates to a surface acoustic wave device containing a quartz substrate and, more particularly, to a surface acoustic wave device which has excellent, stable resonant characteristics achieved by a unique combination of the quartz substrate and electrodes.
2. Description of the Related Art
A surface acoustic wave device containing a quartz substrate serving as a piezoelectric substrate is disclosed in Japanese Examined Patent Publication No. 61-45892.
In the above-mentioned prior art surface acoustic wave device, an interdigital transducer for transmission and reception of signals includes gold electrodes which are disposed on a quartz substrate. The quartz substrate is a quartz rotation Y plate. It is described that the frequency-temperature characteristics of the device are improved by setting X defined by the formula: X={a/(a+b)}(h.sub.0 /.lambda.), where h.sub.0 is the electrode film thickness of the interdigital transducer (hereinafter, referred to as IDT), a is the electrode finger width, b is the electrode finger gap, and .lambda. is the wavelength of a surface acoustic wave to be excited, and a cut direction .theta., so as to satisfy the formula: EQU .theta.=(-18707.5X.sup.2 +21.429X+129.5).
However, in the above-described surface acoustic wave device, Au is used as a material for forming electrodes which defines the transducer IDT. This causes the cost of the device to significantly increase and also makes the process of forming the device extremely difficult.